MOSCOW – A Russian archaeologist claims he's found the lost capital of the Khazars, a powerful nation that adopted Judaism as its official religion more than 1,000 years ago only to disappear, leaving little trace of its culture.

Dmitry Vasilyev, a professor at Astrakhan State University, said his nine-year excavation near the Caspian Sea has unearthed the foundations of a triangular fortress of flamed brick, along with modest, yurt-shaped dwellings, and he believes these are part of what was once Itil, the Khazar capital.

By law, Khazars could use flamed bricks only in the capital, Vasilyev said. The general location of the city on the Silk Road was confirmed in medieval chronicles by Arab, Jewish and European authors.

“The discovery of the capital of Eastern Europe's first feudal state is of great significance,” Vasilyev said. “We should view it as part of Russian history.”

Kevin Brook, the American author of “The Jews of Khazaria,” wrote in an e-mail Wednesday that he has followed the Itil dig over the years, and even though it has yielded no Jewish artifacts, “Now I'm as confident as the archaeological team is that they've truly found the long-lost city.

The Khazars were a Turkic tribe that roamed the steppes from northern China to the Black Sea. Between the seventh and 10th centuries, they conquered huge swaths of what is now southern Russia and Ukraine, the Caucasus Mountains and Central Asia as far as the Aral Sea.

Itil, about 800 miles south of Moscow, had a population of up to 60,000 and occupied 0.8 square miles of marshy plains southwest of the Russian Caspian Sea port of Astrakhan, Vasilyev said.

It lay at a major junction of the Silk Road, the trade route between Europe and China, which “helped Khazars amass giant profits,” he said.

The Khazar empire was once a regional superpower, and Vasilyev said his team has found “luxurious collections” of well-preserved ceramics that help identify cultural ties of the Khazar state with Europe, the Byzantine Empire and even Northern Africa. They also found armor, wooden kitchenware, glass lamps and cups, jewelry and vessels for transporting precious balms dating to the eighth and ninth centuries, he said.

Vasilyev says no Jewish artifacts have been found at the site, and in general, most of what is known about the Khazars comes from chroniclers from other, sometimes competing cultures and empires.

“We know a lot about them, and yet we know almost nothing: Jews wrote about them, and so did Russians, Georgians and Armenians, to name a few,” said Simon Kraiz, an expert on Eastern European Jewry at Haifa University. “But from the Khazars themselves we have nearly nothing.”

The Khazars' ruling dynasty and nobility converted to Judaism in the eighth or ninth centuries.

The study of the Khazar empire was discouraged in the Soviet Union. The dictator Josef Stalin, in particular, detested the idea that a Jewish empire had come before Russia's own. He ordered references to Khazar history removed from textbooks because they “disproved his theory of Russian statehood,” said Yevgeny Satanovsky, director of the Middle Eastern Institute in Moscow.